Preheat the oven to 425°. Place 12 muffin cup liners in muffin pan. Lightly coat liners with cooking spray. Combine oats, brown sugar, dried lavender, and 1 tablespoon of the flour in a medium sized mixing bowl. Drizzle the flour mixture with the melted butter and toss with a fork. Set aside.
In a medium sized mixing bowl, whisk together the flour, baking powder, salt, and baking soda.
Place the oil, sour cream, sugar, oil, vanilla, and egg in another medium sized mixing bowl and whisk to combine thoroughly.
Add the sour cream mixture to the flour mixture and stir until just combined.
Fold the blueberries, Divide the batter evenly among the prepared muffin cups.
Sprinkle the tops of the muffins evenly with the crumb topping. Bake for 5 minutes. Reduce the oven temperature to 375°. Bake an additional 13 minutes, or until a wooden pick inserted in the center comes out clean.
Cool the muffins in the muffin pan for 5 minutes. Remove the muffins from the pan. Cool completely on a wire rack.